https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109632
rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |rsandifo at gcc dot gnu.org
--- Comment #4 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org>
---
Maybe worth noting that if the complex arguments are passed
by value, to give:
struct complx_t {
float re;
float im;
};
complx_t
add(const complx_t a, const complx_t b) {
return {a.re + b.re, a.im + b.im};
}
and SLP is disabled, we get:
fmov w4, s1
fmov w3, s3
fmov x0, d0
fmov x1, d2
mov x2, 0
bfi x0, x4, 32, 32
bfi x1, x3, 32, 32
fmov d0, x0
fmov d1, x1
sbfx x3, x0, 0, 32
sbfx x0, x1, 0, 32
ushr d1, d1, 32
fmov d3, x0
fmov d2, x3
ushr d0, d0, 32
fadd s2, s2, s3
fadd s0, s0, s1
fmov w1, s2
fmov w0, s0
bfi x2, x1, 0, 32
bfi x2, x0, 32, 32
lsr x0, x2, 32
lsr w2, w2, 0
fmov s1, w0
fmov s0, w2
ret
which is almost impressive, in its way.
I think we need a way in gimple of “SRA-ing” the arguments
and return value, in cases where that's forced by the ABI.
I.e. provide separate incoming values of a.re and a.im,
and store them to “a” on entry. Then similarly make the
return stmt return RETURN_DECL.re and RETURN_DECL.im
separately.
